In informed (reference-based) watermark detection, the reference is typically a full resolution copy of the watermarked content, without any of the watermarks to be detected. Use of this high quality reference, especially for detection while outside a trusted environment, constitutes a potential security concern. A potential storage problem could exist as well since large numbers of different high quality movies may need to be stored on the laptop of a field agent.
Therefore, there is a need in the art to provide a reduced resolution reference to detect low frequency watermarks.